Design of multifunctional compliant mechanisms for minimally invasive surgery.

Compliant mechanisms that can perform multiple unique functions have great potential for use in minimally invasive therapy. A fully compliant mechanism may be thought of as a monolithic mechanism without hinge joints which uses elastic deformation to achieve force and motion transmission. Incorporating multifunctional compliant mechanisms into minimally invasive surgical tools has many possible advantages, including reduced instrument exchanges and additional dexterity at the surgical site. Compliant mechanisms also offer the advantage of single-piece construction and ease of manufacture over their rigid-link counterparts, eliminating the need for complex millimeter-scale assembly and cleaning in hinge areas. A multicriteria topology optimization procedure for the design of multifunctional compliant mechanisms is illustrated through the design of a combination tool that will perform forceps and scissor function. A working solid model of the combination forceps/scissors has been generated based on the optimal topology. Results of detailed finite element modeling are discussed along with implications for practical manufacture and implementation.